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Showing papers by "Vienna University of Technology published in 2008"


Journal ArticleDOI
TL;DR: This work assembled 89 scaffolds to generate 34 Mbp of nearly contiguous T. reesei genome sequence comprising 9,129 predicted gene models, providing a roadmap for constructing enhanced T.Reesei strains for industrial applications such as biofuel production.
Abstract: Trichoderma reesei is the main industrial source of cellulases and hemicellulases used to depolymerize biomass to simple sugars that are converted to chemical intermediates and biofuels, such as ethanol. We assembled 89 scaffolds (sets of ordered and oriented contigs) to generate 34 Mbp of nearly contiguous T. reesei genome sequence comprising 9,129 predicted gene models. Unexpectedly, considering the industrial utility and effectiveness of the carbohydrate-active enzymes of T. reesei, its genome encodes fewer cellulases and hemicellulases than any other sequenced fungus able to hydrolyze plant cell wall polysaccharides. Many T. reesei genes encoding carbohydrate-active enzymes are distributed nonrandomly in clusters that lie between regions of synteny with other Sordariomycetes. Numerous genes encoding biosynthetic pathways for secondary metabolites may promote survival of T. reesei in its competitive soil habitat, but genome analysis provided little mechanistic insight into its extraordinary capacity for protein secretion. Our analysis, coupled with the genome sequence data, provides a roadmap for constructing enhanced T. reesei strains for industrial applications such as biofuel production.

1,085 citations



Journal ArticleDOI
TL;DR: An overview of techniques based on dynamic analysis that are used to analyze potentially malicious samples and analysis programs that employ these techniques to assist human analysts in assessing whether a given sample deserves closer manual inspection due to its unknown malicious behavior is provided.
Abstract: Anti-virus vendors are confronted with a multitude of potentially malicious samples today. Receiving thousands of new samples every day is not uncommon. The signatures that detect confirmed malicious threats are mainly still created manually, so it is important to discriminate between samples that pose a new unknown threat and those that are mere variants of known malware.This survey article provides an overview of techniques based on dynamic analysis that are used to analyze potentially malicious samples. It also covers analysis programs that leverage these It also covers analysis programs that employ these techniques to assist human analysts in assessing, in a timely and appropriate manner, whether a given sample deserves closer manual inspection due to its unknown malicious behavior.

815 citations


Journal ArticleDOI
TL;DR: In this article, a combination of logic programming under the answer set semantics with the description logics SHIF(D) and SHOIN(D), which underly the Web ontology languages OWL Lite and OWL DL, is proposed.

576 citations


Journal ArticleDOI
TL;DR: In this paper, various possibilities are discussed how nanoparticles can be protected by organic ligands and how these ligands can be used to introduce functionalities, such as grafting of an already functionalized ligand on the nanoparticle surface, exchanging part or all existing ligands on the particle surface, or grafting a ligand in a nanoparticle followed by modification by organic chemical reactions.
Abstract: Metal or metal oxide nanoparticles possess unique features compared to equivalent larger-scale materials. For applications, it is often necessary to stabilize or functionalize such nanoparticles. Thus, modification of the surface of nanoparticles is an important chemical challenge. In this survey, various possibilities are discussed how nanoparticles can be protected by organic ligands and how these ligands can be used to introduce functionalities. The preparative possibilities include grafting of an already functionalized ligand on the nanoparticle surface, exchanging part or all existing ligands on the nanoparticle surface, or grafting of a ligand on a nanoparticle followed by modification by organic chemical reactions.

466 citations


Journal ArticleDOI
28 Aug 2008-Nature
TL;DR: This work realizes entanglement swapping with storage and retrieval of light, a building block of the BDCZ quantum repeater, and establishes the essential element needed to realize quantum repeaters with stationary atomic qu bits as quantum memories and flying photonic qubits as quantum messengers.
Abstract: At distances beyond about 100 km, quantum communication fails due to photon losses in the transmission channel. To overcome this problem, Briegel, Dur, Cirac and Zoller (BDCZ) introduced the concept of quantum repeaters, combining entanglement swapping and quantum memory to efficiently extend the achievable distances. Their implementation has proved challenging due to the difficulty of integrating a quantum memory. Zhen-ShengYuan et al. realize a building block of the BDCZ quantum repeater, demonstrating entanglement swapping with storage and retrieval of light from atomic quantum memories. Quantum communication is a method that offers efficient and secure ways for the exchange of information in a network. Large-scale quantum communication1,2,3,4 (of the order of 100 km) has been achieved; however, serious problems occur beyond this distance scale, mainly due to inevitable photon loss in the transmission channel. Quantum communication eventually fails5 when the probability of a dark count in the photon detectors becomes comparable to the probability that a photon is correctly detected. To overcome this problem, Briegel, Dur, Cirac and Zoller (BDCZ) introduced the concept of quantum repeaters6, combining entanglement swapping7 and quantum memory to efficiently extend the achievable distances. Although entanglement swapping has been experimentally demonstrated8, the implementation of BDCZ quantum repeaters has proved challenging owing to the difficulty of integrating a quantum memory. Here we realize entanglement swapping with storage and retrieval of light, a building block of the BDCZ quantum repeater. We follow a scheme9,10 that incorporates the strategy of BDCZ with atomic quantum memories11. Two atomic ensembles, each originally entangled with a single emitted photon, are projected into an entangled state by performing a joint Bell state measurement on the two single photons after they have passed through a 300-m fibre-based communication channel. The entanglement is stored in the atomic ensembles and later verified by converting the atomic excitations into photons. Our method is intrinsically phase insensitive and establishes the essential element needed to realize quantum repeaters with stationary atomic qubits as quantum memories and flying photonic qubits as quantum messengers.

442 citations


Journal ArticleDOI
TL;DR: A modular synthetic strategy with which the steric, electronic, and stereochemical properties of the ligands can be varied systematically is developed, which has resulted in the preparation of a range of new pincer complexes, including various iron complexes.
Abstract: Transition metal complexes are indispensable tools for any synthetic chemist. Ideally, any metal-mediated process should be fast, clean, efficient, and selective and take place in a catalytic manner. These criteria are especially important considering that many of the transition metals employed in catalysis are rare and expensive. One of the ways of modifying and controlling the properties of transition metal complexes is the use of appropriate ligand systems, such as pincer ligands. Usually consisting of a central aromatic backbone tethered to two two-electron donor groups by different spacers, this class of tridentate ligands have found numerous applications in various areas of chemistry, including catalysis, due to their combination of stability, activity, and variability. As we focused on pincer ligands featuring phosphines as donor groups, the lack of a general method for the preparation of both neutral (PNP) and anionic (PCP) pincer ligands using similar precursor compounds as well as the difficulty of introducing chirality into the structure of pincer ligands prompted us to investigate the use of amines as spacers between the aromatic ring and the phosphines. By introduction of aminophosphine and phosphoramidite moieties into their structure, the synthesis of both PNP and PCP ligands can be achieved via condensation reactions between aromatic diamines and electrophilic chlorophosphines (or chlorophosphites). Moreover, chiral pincer complexes can be easily obtained by using building blocks obtained from the chiral pool. Thus, we have developed a modular synthetic strategy with which the steric, electronic, and stereochemical properties of the ligands can be varied systematically. With the ligands in hand, we studied their reactivity towards different transition metal precursors, such as molybdenum, ruthenium, iron, nickel, palladium, and platinum. This has resulted in the preparation of a range of new pincer complexes, including various iron complexes, as well as the first heptacoordinated molybdenum pincer complexes and several pentacoordinated nickel complexes by using a controlled ligand decomposition pathway. In addition, we have investigated the use of some of the complexes as catalysts in different C-C coupling reactions: for example, the palladium PNP and PCP pincer complexes can be employed as catalysts in the well known Suzuki-Miyaura coupling, while the iron PNP complexes catalyze the coupling of aromatic aldehydes with ethyl diazoacetate under very mild reaction conditions to give selectively 3-hydroxyacrylates, which are otherwise difficult to prepare. While this Account presents an overview of current research on the chemistry of P-N bond containing pincer ligands and complexes, we believe that further investigations will give deeper insights into the reactivity and applicability of aminophosphine-based pincer complexes.

440 citations


Journal ArticleDOI
TL;DR: This Review summarizes the sources of pollution in current formulations and recent efforts toward "green" pyrotechnics.
Abstract: Fireworks are probably the application of chemistry which resonates best with the general public. However, fireworks and (civil and military) pyrotechnic applications cause environmental pollution and thus have given rise to the development of new, environmentally friendly pyrotechnic compounds and formulations. Nitrogen-rich energetic materials, such as the derivatives of tetrazoles and tetrazines, are about to revolutionize traditional pyrotechnic compositions. This Review summarizes the sources of pollution in current formulations and recent efforts toward "green" pyrotechnics.

402 citations


Journal ArticleDOI
TL;DR: In this article, woodsmoke samples derived from the combustion of beech, oak, spruce, larch and softwood briquettes in a closed stove have been collected and analyzed so as to derive chemical profiles for ambient particulate matter (PM) source apportionment studies, for example, by CMB modelling.

392 citations


Journal ArticleDOI
TL;DR: A computationally fast procedure for identifying outliers is presented that is particularly effective in high dimensions, using simple properties of principal components to identify outliers in the transformed space, leading to significant computational advantages for high-dimensional data.

391 citations


Journal ArticleDOI
TL;DR: In this paper, a global evaluation study was performed on two available global soil moisture products, ERS scatterometer surface wetness data was compared to AMSR-E soil moisture data, pointing out a strong similarity between both products in sparse to moderate vegetated regions with an average correlation coefficient of 0.83.
Abstract: Within the scope of the upcoming launch of a new water related satellite mission (SMOS) a global evaluation study was performed on two available global soil moisture products. ERS scatterometer surface wetness data was compared to AMSR-E soil moisture data. This study pointed out a strong similarity between both products in sparse to moderate vegetated regions with an average correlation coefficient of 0.83. Low correlations were found in densely vegetated areas and deserts. The low values in the vegetated regions can be explained by the limited soil moisture retrieval capabilities over dense vegetation covers. Soil emission is attenuated by the canopy and tends to saturate the microwave signal with increasing vegetation density, resulting in a decreased sensor sensitivity to soil moisture variations. It is expected that the new low frequency satellite mission (SMOS) will obtain soil moisture products with a higher quality in these regions. The low correlations in the desert regions are likely due to volume scattering or to the dielectric dynamics within the soil. The volume scattering in dry soils causes a higher backscatter under very dry conditions than under conditions when the sub-surface soil layers are somewhat wet. In addition, at low moisture levels the dielectric constant has a reduced sensitivity in response to changes in the soil moisture content. At a global scale the spatial correspondence of both products is high and both products clearly distinguish similar regions with high seasonal and inter annual variations. Based on the global analyses we concluded that the quality of both products was comparable and in the sparse to moderate vegetated regions both products may be beneficial for large scale validation of SMOS soil moisture. Some limitations of the studied products are different, pointing to significant potential for combining both products into one superior soil moisture data set.

Journal ArticleDOI
TL;DR: Service mashups facilitate the design and development of novel and modern Web applications based on easy-to-accomplish end-user service compositions.
Abstract: Web services are becoming a major technology for deploying automated interactions between distributed and heterogeneous applications, and for connecting business processes. Service mashups indicate a way to create new Web applications by combining existing Web resources utilizing data and Web APIs. They facilitate the design and development of novel and modern Web applications based on easy-to-accomplish end-user service compositions.

Journal ArticleDOI
TL;DR: In this paper, the authors present an overview on the renewable energy potentials and prospects globally, but based on region and/or country-specific assessments of the resource conditions, the overall energy system boundaries and the related energy policy framework.

Journal ArticleDOI
15 Jul 2008-Sensors
TL;DR: A literature review is made that summarizes the problems encountered when parameterizing soil roughness as well as the reported impact of the errors made on the retrieved soil moisture.
Abstract: Synthetic Aperture Radar has shown its large potential for retrieving soil moisture maps at regional scales. However, since the backscattered signal is determined by several surface characteristics, the retrieval of soil moisture is an ill-posed problem when using single configuration imagery. Unless accurate surface roughness parameter values are available, retrieving soil moisture from radar backscatter usually provides inaccurate estimates. The characterization of soil roughness is not fully understood, and a large range of roughness parameter values can be obtained for the same surface when different measurement methodologies are used. In this paper, a literature review is made that summarizes the problems encountered when parameterizing soil roughness as well as the reported impact of the errors made on the retrieved soil moisture. A number of suggestions were made for resolving issues in roughness parameterization and studying the impact of these roughness problems on the soil moisture retrieval accuracy and scale.

Journal ArticleDOI
TL;DR: In this article, the authors derived quantitative relationships between the amounts of tracer compounds and the number of spores in the atmosphere for different sites in the area of Vienna and obtained over all average relationships of 1.2-2.4 with a clear site dependence.

Journal ArticleDOI
TL;DR: The novel photoinitiators BTMGe or DBDEGe can be used to substitute the binaryphotoinitiator CQ/EMBO in visible light-cured restorative composites and showed an improved UV stability and a storage stability comparable to that of CQ /EMBO-based composites.

Journal ArticleDOI
TL;DR: Scipal et al. as mentioned in this paper proposed a triple collocation error estimation technique to estimate the root mean square error of a set of three independent data sources, including passive microwave (TRMM), active microwave (ERS-2), and modeled (ERA-Interim reanalysis) soil moisture data sets.
Abstract: [1] In the last few years, research made significant progress towards operational soil moisture remote sensing which lead to the availability of several global data sets. For an optimal use of these data, an accurate estimation of the error structure is an important condition. To solve for the validation problem we introduce the triple collocation error estimation technique. The triple collocation technique is a powerful tool to estimate the root mean square error while simultaneously solving for systematic differences in the climatologies of a set of three independent data sources. We evaluate the method by applying it to a passive microwave (TRMM radiometer) derived, an active microwave (ERS-2 scatterometer) derived and a modeled (ERA-Interim reanalysis) soil moisture data sets. The results suggest that the method provides realistic error estimates. Citation: Scipal, K., T. Holmes, R. de Jeu, V. Naeimi, and W. Wagner (2008), A possible solution for the problem of estimating the error structure of global soil moisture data sets, Geophys. Res. Lett., 35, L24403, doi:10.1029/2008GL035599.

Journal ArticleDOI
TL;DR: In this paper, a test scan covering an Iron Age hillfort in the eastern part of Austria was carried out during the first phase of a research project using the latest generation of airborne laser scanners.

Proceedings ArticleDOI
12 May 2008
TL;DR: This work considers the estimation of doubly selective wireless channels within pulse-shaping multicarrier systems (which include OFDM systems as a special case) and proposes a new channel estimation technique using the recent methodology of compressed sensing.
Abstract: We consider the estimation of doubly selective wireless channels within pulse-shaping multicarrier systems (which include OFDM systems as a special case). A new channel estimation technique using the recent methodology of compressed sensing (CS) is proposed. CS-based channel estimation exploits a channel's delay-Doppler sparsity to reduce the number of pilots and, hence, increase spectral efficiency. Simulation results demonstrate a significant reduction of the number of pilots relative to least-squares channel estimation.

Journal ArticleDOI
TL;DR: Numerical results are provided demonstrating not only the feasibility of the method, which has polynomial time complexity, but also its usefulness with regard to practical applications aiming to an understanding of information processing in complex networks.

Journal ArticleDOI
TL;DR: In this article, the authors evaluate simple mapping methods, termed temporal and spatial filters, that reduce cloud coverage by using information from neighboring non-cloud covered pixels in time or space, and by combining MODIS data from the Terra and Aqua satellites.
Abstract: [1] MODIS snow cover products are appealing for hydrological applications because of their good accuracy and daily availability. Their main limitation, however, is cloud obscuration. In this study we evaluate simple mapping methods, termed temporal and spatial filters, that reduce cloud coverage by using information from neighboring non-cloud covered pixels in time or space, and by combining MODIS data from the Terra and Aqua satellites. The accuracy of the filter methods is evaluated over Austria, using daily snow depth observations at 754 climate stations and daily MODIS images in the period 2003–2005. The results indicate that the filtering techniques are remarkably efficient in cloud reduction, and the resulting snow maps are still in good agreement with the ground snow observations. There exists a clear, seasonally dependent, trade off between accuracy and cloud coverage for the various filtering methods. An average of 63% cloud coverage of the Aqua images is reduced to 52% for combined Aqua-Terra images, 46% for the spatial filter, 34% for the 1-day temporal filter and 4% for the 7-day temporal filter, and the corresponding overall accuracies are 95.5%, 94.9%, 94.2%, 94.4% and 92.1%, respectively.

Journal ArticleDOI
TL;DR: In this paper, the authors measured the scattering properties of vegetation and terrain surfaces in a quantitative way, such as the width of the echo pulse and the backscatter cross-section, which is a measure of the electromagnetic energy intercepted and re-radiated by objects.
Abstract: Small-footprint full-waveform airborne laser scanning (ALS) is a remote sensing technique capable of mapping vegetation in three dimensions with a spatial sampling of about 0.5-2 m in all directions. This is achieved by scanning the laser beam across the Earth's surface and by emitting nanosecond-long infrared pulses with a high frequency of typically 50-150 kHz. The echo signals are digitized during data acquisition for subsequent off-line waveform analysis. In addition to delivering the three-dimensional (3D) coordinates of scattering objects such as leaves or branches, full-waveform laser scanners can be calibrated for measuring the scattering properties of vegetation and terrain surfaces in a quantitative way. As a result, a number of physical observables are obtained, such as the width of the echo pulse and the backscatter cross-section, which is a measure of the electromagnetic energy intercepted and re-radiated by objects. The main aim of this study was to build up an understanding of the scattering characteristics of vegetation and the underlying terrain. It was found that vegetation typically causes a broadening of the backscattered pulse, while the backscatter cross-section is usually smaller for canopy echoes than for terrain echoes. These scattering properties allowed classification of the 3D point cloud into vegetation and non-vegetation echoes with an overall accuracy of 89.9% for a dense natural forest and 93.7% for a baroque garden area. In addition, by removing the vegetation echoes before the filtering process, the quality of the digital terrain model could be improved.

Journal ArticleDOI
TL;DR: It is demonstrated that a hardware implementation of the Java virtual machine results in a small design for resource-constrained devices.

Book ChapterDOI
13 Sep 2008
TL;DR: This paper provides a review of contemporary multiobjective approaches based on the singleobjective meta-model-assisted 'Efficient Global Optimization' (EGO) procedure and describes their main concepts and introduces a new EGO-based MOOA, which utilizes the $\mathcal{S}$-metric or hypervolume contribution to decide which solution is evaluated next.
Abstract: Real-world optimization problems often require the consideration of multiple contradicting objectives. These multiobjective problems are even more challenging when facing a limited budget of evaluations due to expensive experiments or simulations. In these cases, a specific class of multiobjective optimization algorithms (MOOA) has to be applied. This paper provides a review of contemporary multiobjective approaches based on the singleobjective meta-model-assisted 'Efficient Global Optimization' (EGO) procedure and describes their main concepts. Additionally, a new EGO-based MOOA is introduced, which utilizes the $\mathcal{S}$-metric or hypervolume contribution to decide which solution is evaluated next. A benchmark on recently proposed test functions is performed allowing a budget of 130 evaluations. The results point out that the maximization of the hypervolume contribution within a real multiobjective optimization is superior to straightforward adaptations of EGO making our new approach capable of approximating the Pareto front of common problems within the allowed budget of evaluations.

Journal ArticleDOI
TL;DR: In this paper, a complete experimental analysis of the shot-to-shot variations of interference-fringe contrast for pairs of independently created one-dimensional Bose condensates is provided.
Abstract: The probabilistic character of the measurement process is one of the most puzzling and fascinating aspects of quantum mechanics. In many-body systems quantum-mechanical noise reveals non-local correlations of the underlying many-body states. Here, we provide a complete experimental analysis of the shot-to-shot variations of interference-fringe contrast for pairs of independently created one-dimensional Bose condensates. Analysing different system sizes, we observe the crossover from thermal to quantum noise, reflected in a characteristic change in the distribution functions from poissonian to Gumbel type, in excellent agreement with theoretical predictions on the basis of the Luttinger-liquid formalism. We present the first experimental observation of quasi-long-range order in one-dimensional atomic condensates, which is a hallmark of quantum fluctuations in one-dimensional systems. Furthermore, our experiments constitute the first analysis of the full distribution of quantum noise in an interacting many-body system. The analysis of the interference fringes generated by initially independent one-dimensional Bose condensates reveals contributions of both quantum noise and thermal noise, advancing our fundamental understanding of quantum states in interacting many-body systems.

Journal ArticleDOI
TL;DR: In this paper, the authors consider the problem of optimal risk sharing of some given total risk between two economic agents characterized by law-invariant monetary utility functions or equivalently, law invariant risk measures.
Abstract: We consider the problem of optimal risk sharing of some given total risk between two economic agents characterized by law-invariant monetary utility functions or equivalently, law-invariant risk measures. We first prove existence of an optimal risk sharing allocation which is in addition increasing in terms of the total risk. We next provide an explicit characterization in the case where both agents’ utility functions are comonotone. The general form of the optimal contracts turns out to be given by a sum of options (stop-loss contracts, in the language of insurance) on the total risk. In order to show the robustness of this type of contracts to more general utility functions, we introduce a new notion of strict risk aversion conditionally on lower tail events, which is typically satisfied by the semi-deviation and the entropic risk measures. Then, in the context of an AV@R-agent facing an agent with strict monotone preferences and exhibiting strict risk aversion conditional on lower tail events, we prove that optimal contracts again are European options on the total risk. MSC 1991 subject classifications: Primary 91B06, 46A20; secondary 91B70.

Journal ArticleDOI
TL;DR: The variety, domain architecture and subgroups of chitinases of filamentous fungi are shown, and how these data integrate with that from molecular biological studies on chit inases are discussed.

Journal ArticleDOI
TL;DR: In this paper, the authors give an overview of the current status and future trends of wear at elevated temperature of selected metallic materials and discuss the salient features which have helped us to gain in depth scientific knowledge of elevated temperature wear are discussed in the light of recent developments.

Journal ArticleDOI
TL;DR: In this paper, the potential of snow cover data from the MODIS satellite sensor for calibrating and validating a conceptual semi-distributed hydrological model was tested for 148 catchments in Austria using the original Terra and Aqua MODIS images as well as MODIS snow cover products.

Journal ArticleDOI
TL;DR: In this paper, the authors argue that much better use should be made of the wealth of hydrological knowledge gained in the past century and that it is essential to expand the information beyond the flood sample at the site of interest.
Abstract: [1] The hydrological literature on flood frequency analysis in the past has placed undue emphasis on solving the estimation problem. In this paper we argue that much better use should be made of the wealth of hydrological knowledge gained in the past century and that it is essential to expand the information beyond the flood sample at the site of interest. We suggest that the expansion of information can be grouped into three types: temporal, spatial, and causal. We present a number of examples from Austria to illustrate the rich diversity of flood processes that are often site specific and difficult to capture by formal methods. On the basis of these examples, and the expansion of information, we illustrate that hydrological reasoning can provide diagnostic findings that give guidance on how to adjust quantitative estimates from formal methods to more fully capture the subtleties of the flood characteristics at the site of interest. We believe that this approach gives a more complete representation of flood processes at a given site than the existing formal methods alone and propose the term “flood frequency hydrology,” as opposed to flood frequency statistics, to reflect the focus on hydrological processes and hydrological reasoning.